Cathodes for Photoinjectors

A while ago, I did a table listing various "family" or types of photocathodes that are used or might be used in an accelerator photoinjector. It was one of the first thing that I did after I changed field and went into accelerator physics. The table made its debut at our Theory Institute workshop on high brightness photoinjector, and it has appeared in the workshop's White paper, but also in several other presentations. So I consider it as the very first impact that I had on a field that I was still trying to learn.

The table is quite brief and obviously omits a lot of other material. I'm working on expanding it to include as many photocathode material that I can find that are either suitable, or being considered as viable candidates for this application. Just because something can photoemit, it doesn't mean it can automatically be used in a photoinjector setting, especially an RF photoinjector. The material must be robust because it will be under high, alternating gradient (often up to 90 MV/m peak field), and it must be able to withstand back bombardment of electrons that are sloshing in the photoinejctor cavity, and must be able to perform for months without significant degradation. All of these are strict requirements of a photocathode for an accelerator photoinejector.

So here is the table that I made years ago. Hopefully, an updated version will be out soon.



Zz.